accord battery light, re-recent post

Accord 2li June 1990, UK right hand, intermitent battery light/no charge New battery New belt, good tension.
I posted a while back - thanks for replies. Went away for a while, but
now at it again.
I have been able to check the following -
When the battery light stays on, the alternator is not charging, ie battery voltage 12.1 with engine running.ABS light comes on with it, goes out with it.
When out - I took it in for testing recently - everything checks out ok.
It is difficult to get it checked professionally when the light is on, since sods law says that as soon as you nearly get there it goes out and all tests ok, which is what happened.
At the monent its staying on, going off, anything from 5 mins to 20 mins.
AFAIK with ignition on, engine not running, with the four pin plug removed - I should be getting battery voltage on all four wires to the plug. ? The alt is a Nippon Denso. It has a plug with four small gauge wires - then a stud with one heavier wire. On this stud I get battery voltage.
I checked this morning, when the light was staying on all the time - with ignition on, engine off, plug removed, I was only getting 4 volts on the white/red wire. I checked this back along the wire, piercing the casing - right back as far as I could trace it, disappearing down among the engine loom.4 volts all along. I can't find a red/white wire emerging anywhere. If this wire is just a 12v ignition + supply, I could just swap it out to a suitable source. I'm tempted to try it just to see - but don't want to cause more problems.
If anyone has a wiring diagram - it would be a help to know what exactly I should be getting on these four wires.and where they are picking up to and their colour code.
Why 'four' - plus the main pos wire on the stud fitting ? Are these alt's machine sensed or battery sensed ?
Quite happy to fit a new alt, but don't want to replace - if the problem is going to re-appear due to something else.
Hopefully, if it stays on in the morning, I've got a mobile car electrician prompted - to catch it while its not charging.
There used to be some shop manuals on-line, but all the links now seem to be defunct - any wiring info on-line ?
Any ideas most appreciated. Geoff - Bristol, UK
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Have the brushes ever been replaced on this alternator? The probability is high they are the problem.
See http://home.earthlink.net/~honda.lioness/id13.html for much of the collective experience of the group on this, mixed in with a bit of my own, lesser hands on. Also, you will find links to service manuals at this site, with wiring diagrams.
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Thanks Elle I have just now found a wiring diagram, searching this group, at the AutoZone site. My white/red, and white/green are going to engine control. Leaving a normal two - one 12v, one via warning light, with the 80 amp main charging lead. Will check out your link, nonetheless - many thanks, Geoff.
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